Reference soil Kenya 13: Solonetz

KE013

Solonetzes occur where a sodium source supplies the clay-rich subsoil with exchangeable Na, causing peptization of clay and organic substances and deterioration of the topsoil.

Characteristics

Soils having a natric horizon (a subsurface horizon with distinct higher clay content than the overlying horizon and more than 15% exchangeable sodium) within 100 cm from the soil surface.

Distribution of Solonetz (rough estimation supplied by soilgrids)

Reference soil KE013: Solonetz

A moderately well drained brown to yellowish brown soil with a moderately sodic subsoil and moderate surface sealing (3mm), derived from fine-grained sandstones and siltstones (Upper Maji-Ya-Chumvi beds). Below 35 cm mottles appear coloured strong brown, increasing with depth; termite mounds (4-7m diameter, 1,5 m height) exist. (R3 pg 253)

Classification

WRB 2006

WRB 1998

Stagnic- Solonetz (Albic Abruptic Magnesic)

Stagni-Mazic- Solonetz (Albic)

20-65 cm	albic horizon
65-120 cm	natric horizon
-	reducing conditions
-	abrupt textural change
-	stagnic colour pattern

FAO-UNESCO-ISRIC 1988

FAO-UNESCO-ISRIC 1974

Orthi-Stagnic Solonetz

Solodic Planosol

0-20 cm	ochric A horizon
20-65 cm	albic E horizon
65-120 cm	natric B horizon
-	abrupt textural change
-	stagnic

0-20 cm	ochric A horizon
20-65 cm	albic E horizon
65-120 cm	natric B horizon
-	abrupt textural change

Other classification

USDA-NRCS (1999)	Arenic Natrustalf
USDA-SCS (1975)	Arenic Natrustalf ustic

More images

Physical characteristics

Particle size distribution

Depth (cm)	Gravel % v/v	very coarse sand % w/w	coarse sand % w/w	medium sand % w/w	fine sand % w/w	very fine sand % w/w	Total sand % w/w	coarse silt % w/w	fine silt % w/w	Total silt % w/w	Clay % w/w
0-20	-	0.1	0.1	0.5	47.9	28.5	77.1	11.9	3.7	15.6	7.5
20-35	-	0.1	0.1	0.4	45.9	30.0	76.5	11.0	5.0	16	7.7
35-56	-	0.2	0.1	0.4	46.1	29.3	76.1	12.4	4.2	16.6	7.4
56-70	-	0.0	0.1	0.3	50.0	29.3	79.7	12.0	5.2	17.2	3.2
65-80	-	0.1	0.2	0.4	41.7	26.5	68.9	10.9	4.5	15.4	15.9
100-120	-	0.1	0.2	0.3	41.1	25.5	67.2	11.4	4.5	15.9	17.1

Water retention characteristics

Depth (cm)	Bulk density kg/dm³	Spec. Surf. Area m²/g	COLE cm/cm	Water disp. clay %	Clay % w/w
0-20	-	-	-	2.9	7.5
38-43	1.37	-	-	-	-
20-35	-	-	-	3.6	7.7
78-83	1.66	-	-	-	-
35-56	-	-	-	2.8	7.4
56-70	-	-	-	2.4	3.2
65-80	-	-	-	13.3	15.9
100-120	-	-	-	-	17.1

Other physical data

Depth (cm)	Bulk density kg/dm³	pF 0 % v/v	pF 1.0 % v/v	pF 1.5 % v/v	pF 2.0 % v/v	pF 2.3 % v/v	pF 2.7 % v/v	pF 3.4 % v/v	pF 4.2 % v/v
38-43	1.37	41.3	40.4	35.8	17.7	11.4	8.1	1.3	0.3
78-83	1.66	28.2	28.1	28.2	23.5	20.9	18.4	8.5	7.2

Chemical data

Depth (cm)	pH H2O	pHKCl	EC 1: 2.5 dS/m	CaCO3 % w/w	C % w/w	N %	C / N	Exch. Acid cmol(c)/kg	Exch. Al cmol(c)/kg	Ca cmol(c)/kg	Mg cmol(c)/kg	K cmol(c)/kg	Na cmol(c)/kg	Sum Cations cmol(c)/kg
0-20	4.5	3.8	0.06	-	0.40	0.04	10	1.1	0.9	0.4	0.5	0.1	0.0	1
20-35	4.5	3.8	0.05	-	0.31	0.02	16	1.2	1.1	0.2	0.7	0.1	0.0	1
35-56	4.7	3.8	0.05	-	0.23	0.02	12	1.0	0.9	0.2	0.8	0.1	0.0	1.1
56-70	4.8	4.0	0.08	-	0.12	0.01	12	0.2	0.0	0.2	0.5	0.0	0.3	1
65-80	5.2	3.8	0.33	-	0.25	0.02	13	0.4	0.2	0.2	3.0	0.1	1.3	4.6
100-120	7.5	5.5	0.80	-	0.10	0.01	10	0.0	0.0	0.2	3.1	0.1	2.1	5.5

Depth (cm)	Base sat. %	CEC soil cmol(c)/kg	CEC clay cmol(c)/kg	CEC org cmol(c)/kg	ECEC cmol(c)/kg	Al sat. %	ESP %
0-20	38	2.6	16	1.4	-	35	0
20-35	43	2.3	16	1.1	-	48	0
35-56	42	2.6	24	0.8	-	35	0
56-70	111	0.9	15	0.4	-	0	33
65-80	85	5.4	29	0.9	-	4	24
100-120	92	6.0	-	0.4	-	0	35

Depth (cm)	pH NaF	P Retention %	ODOE	Al o % w/w	Si o % w/w	Fe d % w/w	Al d % w/w	Fe p % w/w	Al p % w/w	C p % w/w	Fe o % w/w
0-20	-	-	-	0.04	0.00	0.20	0.06	0.04	0.06	-	0.04
20-35	-	-	-	0.05	0.00	0.23	0.05	0.06	0.11	-	0.05
35-56	-	-	-	0.04	0.00	0.19	0.04	0.06	0.10	-	0.06
56-70	-	-	-	0.02	0.00	0.14	0.03	0.03	0.02	-	0.04
65-80	-	-	-	0.05	0.00	0.28	0.04	0.07	0.19	-	0.12
100-120	-	-	-	0.04	0.00	0.33	0.05	0.04	0.13	-	0.02

Elemental composition of the soil

Depth (cm)	Al2O3 % w/w	CaO % w/w	Fe2O3 % w/w	K2O % w/w	MgO % w/w	Na2O % w/w	SiO2 % w/w	TiO2 % w/w
0-20	6.1	0.06	0.7	2.50	0.07	-	87.7	0.56
20-35	6.4	0.06	0.8	2.46	0.09	-	87.1	0.56
35-56	6.5	0.07	0.8	2.45	0.10	-	89.3	0.57
56-70	5.5	0.07	0.5	2.52	0.04	-	91.1	0.55
65-80	8.3	0.05	1.4	2.37	0.24	-	85.5	0.63
100-120	9.0	0.05	1.5	2.56	0.24	-	85.7	0.67

Depth (cm)	Al2O3/Fe2O3 mol/mol	LOI % w/w	MnO2 % w/w	P2O5 % w/w	SiO2 / Al2O3 mol/mol	SiO2/Fe2O3 mol/mol	SiO2 / R mol/mol
0-20	13.6	1.3	0.00	0.00	24.4	333	22.7
20-35	12.5	1.4	0.00	0.00	23.1	289.4	21.4
35-56	12.7	1.2	0.00	0.01	23.3	296.7	21.6
56-70	17.2	0.5	0.00	0.00	28.1	484.2	26.6
65-80	9.3	2.0	0.00	0.01	17.5	162.3	15.8
100-120	9.4	1.8	0.00	0.00	16.2	151.8	14.6

Clay mineralogy

Depth (cm)	Chlorite	Feldspar	Gibbsite	Goethite	Halloysite	Hematite	Kaolinite	Mica / illite	Mixed-layer	Quartz	Smec	Vermiculite
0-20	-	weak to medium	-	-	-	-	medium to strong	very weak to weak	weak to medium	weak to medium	-	-
20-35	-	weak to medium	-	-	-	-	medium to strong	very weak to weak	weak to medium	weak to medium	-	-
35-56	-	weak to medium	-	-	-	-	medium to strong	weak	weak to medium	weak to medium	-	-
56-70	-	weak to medium	-	-	-	-	medium to strong	weak	weak to medium	weak to medium	-	-
65-80	-	weak to medium	-	-	-	-	strong	weak	weak to medium	weak	-	-
100-120	-	weak to medium	-	-	-	-	strong	weak	medium to strong	weak	-	-

Profile description

Ah 0-20 cm	pale brown (10YR 6/3, dry) dark brown (10YR 3/3, moist)fine sandy loam,porous massive to weak medium subangular blocky,hard friable non sticky non plastic,few fine and medium pores,non calcareous,gradual smooth boundary to,
E1 20-35 cm	light yellowish brown (10YR 6/4, dry) dark yellowish brown (10YR 4/4, moist)fine sandy loam,porous massive to weak medium subangular blocky,hard friable non sticky non plastic,common fine pores,non calcareous,clear smooth boundary to,
E2 35-65 cm	light yellowish brown (10YR 6/4, dry) dark yellowish brown (10YR 4/4, moist)loamy fine sand,porous massive to weak medium angular blocky,hard friable non sticky non plastic,common (5-15%) fine faint mottles (7.5 YR 5/6),common very fine pores,non calcareous,abrupt smooth boundary to,
Btng 65-120 cm	light brownish grey (10YR 6/2, dry) yellowish brown (10YR 5/6, moist)sandy clay loam,massive,extremely hard firm slightly sticky slightly plastic,many (15-40%) coarse distinct mottles (7.5 YR 5/6),few very fine pores,non calcareous,

Kind 1 (parent material) ; Parker (eds), 1984	sandstone/siltstone
Mode of accumulation or deposition of parent material	residual material
Remarks on Parent Materials	Upper Maji-ya-Chumvi beds
Texture of parent material	loamy
Weathering Resistance	moderate
General characterization of the status of weathering of solid rock	partially or moderately

Intensity of the soil erosion type	slight
Intensity of the soil erosion type (second entry)	slight
Soil erosion type	sheet
Soil erosion type (second entry)	gully

Land use or vegetation in the immediate vicinity of the site	extensive grazing
Remarks on Land Use / Vegetation	VEGETATION: Wooded bushed grassland
Major vegetation type; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	grassland

Altitude	216m
Physiographic Unit	coastal uplands
Physiographic position of the site	slope
Regional landform; McDonald, R.C., Isbell, R.F. et all, 1984; Australian soil and land survey Field Handbook, Inkata Press, Melbourne.	plain
Slope	4%
Topography; Guidelines for soil description - Fourth edition (FAO, Rome, 2006)	undulating

Drainage class ; FAO (2006) - Guidelines for soil description	moderately well
Flooding frequency (FAO, 1986)	never
Depth to groundwater table	0cm
(Estimated) minimum (upper) depth to groundwater table	0cm
Estimated permeability (class) of least permeable part of the profile	slow
Estimated run off (class)	medium

Evidence of alkali ; Soil Survey Manual USDA, 1951	non-alkaline
Slaking of aggregates by tillage, rainfall or frost (USDA/SCS, 1979)	surface partly slaked, round smooth aggregates
Microrelief Height: variation in height	150
Micro relief type: small-scale differences in relief in the direct vicinity of the site (FAO, 1986)	termite/ant mounds
Microrelief pattern	isolated
Rock outcrop class (FAO (2006) - Guidelines for soil description)	none
Evidence of salt; Soil Survey Manual USDA, 1951	non-saline
Surface stoniness class (FAO (2006) - Guidelines for soil description)	none

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Reference soil Kenya 13: Solonetz

Characteristics

Reference soil KE013: Solonetz

Classification